Plant physiological responses and sensing approaches to implement precision irrigation in Mediterranean fruit orchards

The Mediterranean basin is recognized as one of the most vulnerable regions to climate change, with an increased frequency of extreme events, including heat waves and prolonged droughts, as well as intense rainfall during short periods throughout the year. In semi-arid environments, where water resources are limited, accurate determination of irrigation timing and volumes is essential at farm level for sustainable irrigation management. Years of research have focused on optimizing not only irrigation, but also all aspects of fruit orchard systems (olive, apricot, peach and kiwifruit) grown in a Mediterranean environment, with the aim of increasing soil fertility and water use efficiency, saving water and reducing environmental impact. Of the fruit crops addressed, kiwifruit is the most profitable and has great social value in terms of increasing local opportunities. However, it requires careful management of water resources. Irrigation management in kiwifruit orchards along the Italian peninsula is still inaccurate, with significant seasonal water excess and losses on the one hand, and the establishment of plant water deficits on the other. In a three-year study, innovative monitoring approaches based on sensing tools and techniques were used to increase knowledge of the water stress response of kiwifruit. Comprehensive sensor-based monitoring of site-specific environmental variables, soil and plant water status was carried out for increasingly precise irrigation in kiwifruit orchards. The combination of soil and plant monitoring helped to understand the actual physiological status of the vines and to define soil moisture levels that did not limit plant performance. A mechanistic model integrated with continuous plant sensor measurements was developed and could be useful in implementing easy-to-use irrigation tools for precise, real-time irrigation management in fruit crops in semi-arid environments. The application of precision irrigation in a commercial kiwifruit orchard over three years allowed savings of up to 30% of the irrigation volume. Further research is needed to validate practices and tools and to fill the gap between current irrigation practices and what is scientifically considered best practice in fruit orchards. The appropriate design and management of irrigation methods, together with optimized management of orchard systems, can help save water and mitigate environmental hazards, especially in Mediterranean conditions.